First, look at where Republicans and Democrats tend to live. David Jarman took a detailed look recently, with great charts and interactive maps, at the relative growth in Democratic and Republican votes in the nation’s 3,144 counties between 1988 and 2012. For each county, Jarman calculates the net change in Democratic votes (increase in Democratic votes minus increase in Republican votes) over that time period.

The results are fascinating for how much and where growth is benefiting Democrats and Republicans. Start with the Democrats. The 25 top counties for net Democratic vote gain include many of the most populous counties in the country. They include Los Angeles at the top, eight of the ten most populous (LA, plus Cook [Chicago], San Diego and Orange [CA], Dallas, Kings [Brooklyn], Queens and Miami-Dade) and 15 of the top 25 most populous. The rest, without exception, are large counties that include a major city or are urbanized inner suburbs of a major city. The magnitude of Democratic gains in the top 25 ranges from 1.2 million in LA down to around 140,000.

The top gainers for the GOP, in contrast, tend to be in much smaller counties on the periphery of metropolitan areas (“exurbs”). The top 25 GOP gainers include no county in the US top 25 in population and include only one in the top 50. And the magnitude of GOP gains in the top 25 is much smaller than those enjoyed by the Democrats. Indeed, the largest GOP net gain of all—90,000 in Provo county, Utah–is not only smaller than the 25th ranked gain for the Democrats (140,000) but also smaller than Democratic gains all the way down to the 61st ranked Democratic gainer county.

Democratic strength in dense areas is clearly one reason for the Democrats’ increasing electoral potency, particularly in Presidential elections. Conversely, the concentration of GOP gains in more lightly-populated areas limits their strength now and in the future.

Second, take a peek at what Democrats and Republicans learn. A recent Pew Research Center report examined educational attainment trends by generation, particularly in terms of the payoff obtained by a college degree, combined with a recent survey of public opinion on the usefulness of a college education.

The report notes that 34 percent of Millennial generation 25-32 year olds have a four year college degree, compared to 25 percent among Gen Xers at the same age, 24 percent among both late and early Boomers and just 13 percent among those from the Silent generation. Millennials are also receiving the highest relative values from their degrees. A Millennial college graduate has median earnings of $45,500, compared to just $28,000 for a Millennial high school graduate. Back in 1965, the gap was much narrower: a Silent Generation college graduate earned $38,800 (2012 dollars) while a high school graduate earned $31,400.

Millennial college graduates also do very well in terms of unemployment (just 3.8 percent vs. 8.1 percent among those with some college and 12.2 percent among high school graduates) and poverty incidence (5.8 percent vs. 14.7 percent among those with some college and 21.8 percent among high school grads). These data should put to rest any notion that it is somehow not worth it for Millennials to invest in a college education.

That is certainly how Millennial college grads see the situation. In the accompanying public opinion survey, 88 percent said that, considering what they and their family paid for their education, their degree has already paid off (62 percent) or would pay off in the future (26 percent). In addition, 86 percent of employed Millennial college grads describe their current job as a career or career-track job, compared to 73 percent of those with some college and only 57 percent of high school grads.

These trends have important political implications. First, the continued rise in the proportion of college graduates is a powerful factor moving us toward a more open and tolerant society (see this report from CAP). It also should reduce Democratic deficits among white voters since white college graduates are considerably less hostile to Democrats than white noncollege voters.

Second, these data indicate that, despite the existence of some mismatches between education and job (e.g., college grads from fancy schools who work as baristas or cab drivers), a college degree by and large remains the gateway to a satisfying and middle class life. That means making a college education attainable and affordable for a much larger segment of the population should be a high priority for progressives. And since the GOP’s commitment to enhancing economic mobility, as Sean McElwee has pointed out, is full-throated and unequivocal — except when it involves spending money — this is an issue where Democrats can draw a particularly sharp contrast between themselves and the GOP.

Finally, we’ve got a basic question of how old Republicans and Democrats are. Most coverage of generational politics focuses on the rising (and very liberal) Millennial generation. That is understandable, but there is more to generational politics than just one generation. It turns out, according to a new Gallup report, Baby Boomers (folks born from 1946-64) are also exerting a progressive pull on American politics:

Baby boomers constitute 32% of the U.S. adult population and, by Gallup’s estimate, 36% of the electorate in 2012, eclipsing all other generational groups. Baby boomers have dominated U.S. politics on the basis of their sheer numbers since the late 1970s, when most of the group had reached voting age….If the party preferences of each generational group were to hold steady in the coming years as the Democratic-leaning baby boomers gradually replace the more Republican Silent and Greatest generations, the country as a whole would likely become more Democratic.

Thus, over time, high-turnout seniors, currently the most conservative part of the electorate by age, will be liberalized as Baby Boomers age. Moreover, the most liberal part of the generation — those born up through 1955 and termed “early Boomers” — is frontloaded, so the political impact on the senior population could be fairly rapid.

So, the changing location, education levels, and age of the electorate suggest why the Republicans’ long-term disadvantages aren’t so bad as most people think. They’re worse.